- Originally published June 3, 2015 at 9:02 pm Updated June 4, 2015 at 2:46 pm

A dye derived from deathstalker scorpion venom that illuminates cancer cells during surgery has been approved for testing in kids and young adults at Seattle Children’s, officials said.

By JoNel Aleccia Seattle Times health reporter

A dye derived from scorpion venom that lights up cancer cells so surgeons can see — and remove — deadly brain tumors will be tested for the first time in children, Seattle experts said Thursday.

Officials with the Food and Drug Administration (FDA) have expanded approval to enroll patients from infants to young adults in a clinical trial of the Blaze Bioscience drug BLZ-100, known as Tumor Paint.

“I think it does have the potential to be revolutionary,” said Dr. Sarah Leary, a pediatric neuro-oncologist at Seattle Children’s who is the principal investigator for the trial.

The first of 27 young patients up to age 30 with devastating brain tumors could begin enrolling within weeks, Leary said.

The move follows FDA approval last fall of the first U.S. human clinical trials of the drug pioneered by Dr. Jim Olson, a pediatric brain-cancer expert at the Fred Hutchinson Cancer Research Center.

It aims to solve a stubborn problem: how to target malignant cells during surgery without removing healthy cells as well.

“This particular Tumor Paint program came from a patient who had cancer left behind,” Olson said. “We just became fiercely dedicated to giving surgeons a tool that would provide a way to distinguish cancer cells from normal brain.”

The phase I clinical trial — which tests safety, dosage and side effects in a small number of patients — was funded by an $800,000 grant from the nonprofit group Gateway for Cancer Research.

BLZ-100 is a molecule discovered and first developed by researchers at Fred Hutch, Seattle Children’s and the University of Washington. It consists of two parts, a protein derived from deathstalker scorpion venom that penetrates the tumor cells, and a dye that glows fluorescent in near-infrared light.

Olson discovered the scorpion-venom use after sorting through thousands of other potential sources in nature. It’s chemically produced now, with no actual venom involved.

It appears to work by binding to a target protein on the surface of the cancer cells, which isn’t present in normal cells, Olson explained.

The trial in children follows treatment of nine adults with Tumor Paint, including seven patients at Cedars-Sinai Medical Center in Los Angeles. Two others have been treated at a trial site in Australia.

So far, the drug appears safe in adults, said Dr. Chirag Patil, a neurosurgeon at the Brain Tumor Center at Cedars-Sinai.

“From a safety perspective, it’s certainly been a relief,” he said. “Whenever you test it for the first time in humans, you are always worried about a new agent.”

In adults, the trial patients have deadly glioma brain tumors. But in children, there may be a wide range of types of brain tumor appropriate for use with Tumor Paint.

“It’s devastating to have child go through an eight-hour surgery, and think they made it, and then two days later on an MRI, you see a little lump is left,” Leary said.

Tumor Paint’s precise targeting of the cancer cells could reduce the need for second surgeries and improve survival, she said. Leary expects some of the clinical-trial patients will travel from other countries for the chance at treatment.

“This is the only place in the world that this will be offered,” she said.

So far, the drug appears to light up cancer cells and leave healthy cells alone, at least in specimen tests in the laboratory, Patil said. Researchers are waiting to test the fluorescence in the operating room, until they can also test a new device that can provide light in the tiny space available during surgery.

“One of the challenges of the drug itself is, do we have the right dose,” she said. “The other challenge is, do we have the right kind of device to get the light where we need it?”

This isn’t the first drug that aims to light up tumors, said Dr. David Roberts, a professor of surgery at Dartmouth’s Geisel School of Medicine. He and others are testing another compound, 5-aminolevulinic acid (5-ALA), which targets glial tumors. He said the work of Olson and others “is not a whole new paradigm, but it’s an important one.”

And Dr. Robert Naftel, a pediatric neurosurgeon at Vanderbilt University Medical Center, cautions that the trial is still in its earliest stages and it will take more research — and further trials — to determine if the drug affects overall survival and progression-free survival in patients.

“It is early at this time to champion this technology as a game-changer in treating brain tumors,” he said.

The Seattle Children’s trial is expected to run for two years. If all goes well in kids and adults, Tumor Paint could be available widely within three to five years, said Heather Franklin, president and chief executive of Blaze Bioscience.

For Leary and for Olson, who both also work at Seattle Children’s Research Institute, the launch of the local trial brings the idea and the delivery of the drug full circle.

“The ability to take a clinical problem and coordinate it between my work at Children’s and Fred Hutch is amazing,” Olson said. “To have our clinical trials coordinate with our clinical vision is beautifully aligned.”

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